Telephone-exchange system



TELEPHONE EXCHANGE SYSTEM Filed Jan. 17, 1928 Patented Dec. 3, 1929 UNITED STATES PATENT FEFEQE.

CLARENCE B. FOWLER, OF QUEENS VILLAGE, NEW YORK, `.ASSGNOR TO BELL TELE :PHONE LABORATORIES, INCORPORATED, GF NEW YORK, N. Y., A CORPORATION 0F NEW YORK TELEPHONE-EXCHANGE SYSTEM Application :tiled January 1*?, 1928. Serial No. 247,277.

This invention relates to telephone eX- change systems and particularly to systems in which the service charge is based on the duration of conversation.

The objects areto improve the service rendered to subscribers on lines equipped with substation meters and to secure greater re liability in the operation of the central oiiice controlling circuits.

It has been proposed in the past to charge a calling subscriber for the service rendered by operating a meter, located at his substation, by reversing the current in the calling line at successive intervals during the period the conversational connection is established between his line and the called line. To this end a current reversing device is provided at the central oiiice and is rendered effective either when connection is completed to the calling line, as by the insertion of the answering plug of a cord circuit,or when the called party answers. These prior systems, however, have not taken into account the dierent classes of called lines.

According to the present invention an iinprovement is secured in the service available to the calling subscriber by the provision of means for discriminating between calls for which the usual periodic charge should be made vduring conversation and calls for which no charge should be made, such as calls to operators. When this discriminating means is operated the device for periodically reversing current in the calling line is rendered ineffective so that no charge can be made.

A feature of the invention is a circuit arrangement in which the calling subscribers supervisory relay may release momentarily due to the reversal of current in the line without affecting the supervisory signal.

The drawing illustrates a portion of a telephone system in which the subscribers lines appear at an operators position. Two ot these-lines, A and B, are shown terminating in jacks 3 and 5 respectively at the operators position. The lines Aand B are equipped respectively with meters 1 and 2 located at thesubstations. These meters are arranged to operate at successive intervals during the conversation 1n response to "successive reversals of current in the line. The central office circuits are so arranged that only the metler of the calling subscribers line is actuatec The operators position is equipped with a number ci cord circuits such as the cord circuit C shown partly in detail in the drawing. A current reversing circuit 20 is provided in common to a plurality of cord circuits C. It is arranged to be associated with any particular cord circuit taken in use to supply current to the calling` subscribers line and to automatically reverse the direction of current iiow in the line at successive intervals during the conversational period. The supply circuit 2() includes a source of current 21, a reversing relay 22, an interrupter 23, impedance coils 24 and 25, and a condenser 26.

The cord circuit C is provided with an individual relay 18 which serves to connect the supply circuit 2O through the left windings of the repeating coil 7 to the tip and ring conductors of the calling line A. Similar relays are provided for the other cord circuits.

A detailed description will now be given of the manner in which the system operates. Assume that the subscriber on the line A wishes to hold conversation with the subscriber of line B. The calling subscriber initiates the call in the usual manner and the operator responds by inserting the plug 4l of the cord circuit in the jack 3. When the plug is inserted in the jack, a circuit is completed from battery through the lamp 1li, resistance 15, back contact of relay 13, conductor 28, to ground through the sleeve oil' the plug and jack. At the same time another circuit is completed from battery through the right back contact of relay 18, lower left winding oft repeating coil 7, supervisory relay 8, contact of key 10, over the ring side of the subscribers line, and returning over the tip side through the contact of key 10, upper left winding of coil 7 to ground at the left back contact of relay 18. The relay 8 operates in this circuit and completes a circuit from the interrupter 19, right back contact of relay 12, contact of relay 8,resistances 16 and 15. baclr contact of relay 18 to the grounded conductor 28. Each time the interrupter closes, the cir f' ao Next, the operator manipulates her talking key 11 to connect her telephone set to the cord circuit and converses V,with the calling subscriber. The depression of the talking key 11 completes an obvious circuit through the left winding of the slow-release relay 12. Relay 12'operates and locks in a' -circuit from ground through the right Winding and contact thereof, contact of relay 8, to battery at the inner left contact of relay 12. Relay 12 at'its right back contact opens the circuit to the interrupter 19to discontinue the flashing of the lamp 14:. The lamp 14 is now conipletely shunted by a circuit from battery through the left contact of relay 12, resistances 16 and '15, back contact of relay 13 to the vgrounded sleeve conductor 28. The lamp 14, is, therefore, extinguished.

v The operator, having obtained the number of the called line, seizes the plug 6 and inserts it in the jack 5; Following this the operator applies ringing current to the called `line in the Well-known manner. When the called subscriber answers, a. circuit is completed fromk battery through the lower right Winding of coil 7, supervisory relay 9, thence over the ring side `of the called subscribers Aline B, and returning over the tip side through the upper right Winding of the coil 7, to ground. The supervisory relay 9 operates and closes an obvious circuit for relay 17. Relay 117 completes a circuit from ground f through thel left contact of relay 13, contact of relay 17, to battery through the Winding of'relay 18. The relay 18 operates and conlnectsfthe battery supplvcircuit 20 to the calling line. Assuming the relay 22 is deenery gized at the timerelay 18 operates, the circuit for supplying talkingA current may be tracedA from battery 21, lower back contact of relay 22, coil 25, right front contact of relay 18 through the lower left Wind ing of coil 7 ,thence over the loop of the calling line A,

yce

and returning through the` upper left Wind- Aing of coil 7, left front contactV of relay 18,

coil 24, upper4 left contact of relay. 22 to ground. The connection is now in condition for the' subscribers to' conversewith each other. f

Atthe end ofA measured intervals during the conversation theinterrupter 23 causes the relay 22 to energize and release. For example, relay 22 may operate and remain op-` eratedfor a 15-second period and then release andremain released for another' 15-second period, the 'cycle' being repeated.l Whenthe relay 22 operates it reverses the direction of current ilowingffrom theV source' 21 over the calling-'subscribers line, thereby causing the operation of ltheZola'1f-ized message meter l.

Thel cl'icke'feoils and 25i'a'nd theV condenser in the line due to the reversing operation.

At the end of conversation the subscribers replace their receivers on the switchhooks. Vhen the called subscriber hangs up his rcceiver relay 9 releases, releasing the relay 17 Which in turn opens the circuit of relay 18. Relay 18 releases, disconnecting the reversing circuit 20 from the calling line to prevent further operation of the meter 1.

If the calling subscriber hangs up his receiver irst, his line is opened at the switchhook contacts to render the meter operating circuit ineffective. The calling subscriber by replacing his receiver on the switchhook opens the circuit of supervisory relay 8 which in turn opens the holding circuit of relay 12. Relay 12 releases and removes the shunt -from the lamp 14. The lamp 14 accordingly lights and remains lighted until the operator removes the plug 4 from the jack 3.

Tt will be noted that the circuit of the calling line is opened momentarily at the contacts of relay 22 on each reversal of current. These interruptions of the line, although brief, are likely to result in corresponding releases by the supervisory relay 8. lVith the usual controlling circuit for the supervisory lamp, the release of the supervisory relay would bc likely to cause the lamp to flicker. This unstandard operation of the lamp would probably confuse the operator and might result in an impairment of the service given the subscriber. According to the present arrangement, however, the momentary release of the supervisory relay 8 has no effect upon the lamp 14. Thisis due to the fact that the control of the lamp is removed from the relay 8 and placed with the relay 12 as above explained. Although the relay 8 on releasing momentarily opens thc holding circuit of relay 12, the relay 12 does not retract its armatures due to its slow-release character.

If the calling subscriber wishes to recall the opera-tor he depresses the switchhook 1110-. l mentarily and then releases it.

The depression of the switchhook opens the circuit of relay 8, causing the release of relay 12. When relay 8 again operates a circuit is completed from the interrupter 19, through the right back Contact of relay 12, contactof relay 8, resistances 16 and 15 right back contact of relay 13 to the sleeve conductor 28. The interrupter 19 causes the lamp 14 to flash to attract the operators attention.

Assume next that the calling subscriber Wishes to establish a connection with the information operator, or with some line for which no charge should be made. The operator answersthe call in the same manner and upon learning the called number inserts the plug 6 in the jack 2 of trunk T. The trunk T may lead to the information operators position. The operator knowing that the call is a free one, actuates the hey momentarily. Iey 1() completes a circuit from battery, through the lamp 14, winding of relay 13, contacts of said key, to ground through the sleeve contacts of the plug and jack. Relay 13 operates and loclrs through its right front contact to the grounded sleeve conductor 28. When the relay 12 operates as above explained it completes a circuit from battery through its inner lett contact, resistn ance 16, winding and contact of relay 13. to the grounded sleeve conductor 23. This circuit shunts the lamp 14 to extinguish it.

lfilhen the called party answers the supervisory relay 9 operates, operating in turn the relay 17. Since the relay 13 is energized, however, relay 17 is inetlective to operate the relay 13. Accordingly the reversing circuit 2O is not connected to the calling subscribers line during conversation and no actuation ot' the meter 1 takes place.

While the invention has been illustrated in connection with a manual system it is to be understood that it may be applied to systems employing automatic switches. It is also to be understood that numerous changes and alterations may be made and that the scope of the invention is to be limited only by the appended claims. i

The meters at the substations are illustrated in diagrammatic manner and may be o1 any suitable construction. For example, reference is made to the register shown in the patent to Thomson, No. 1,121,953, grant-- ed December 22, 1914.

That is claimed is:

1. In a telephone system, a calling line and a number oi called lines, means for interconnectinnsaid calling line and any one of said called lines tor conversation, a meter at the substation of the calling line, a device for repeatedly changing the ilow of current in `he calling line during conversation to actu ate said meter, and means for rendering said device ineffective to discriminate between certain of said called lines.

2. In a telephone system, a calling line and a plurality ot1 called lines, means for establishing a connection. between the calling line and any one oi said called lines, a meter at the substation of the calling line, a device for repeatedly reversing the direction ot current flow in the calling line to actuate said meter, and means for rendering said device ineffective to discriminate between certain of said called lines,

3. In a telephone system, a calling line and a number of called lines, means for interconnecting the calling line and any one of said called lines1 a message meter individual to the calling line, a device for periodically reversing the flow ot current in the calling line to operate said meter during conversation, means controlled by the called subscriber to render said device effective, and means for rendering said device ineiiective to discriminate between certain of said called lines. y

4. In combination, a calling line and a plurality of called lines, a meter for the calling line, an operators position, a cord circuit at said position for establishing connection between the calling line and one of said called lines, a device for repeatedly changing the tlow oli current in the calling line to actuate said meter, and means controlled at the will et' the operator jor rendering said device ineii'ective.

5. In a telephone system, a calling line, two called lines oi diil'erent classes, a meter for the calling line, means tor establishing` a connection between the calling line and either ot said called lines,`a device for reversing the flow of current in the calling line to repeatedly operate said meter, and means for rendering said device ineffective to discriminate between said ca led lines.

6. In combination, a calling line and a called' line, means for interconnecting said lines, a meter at the substation ot the calling line, a supervisory relay in circuit with the calling line, a signal controlled by said relay, means 'tor repeatedly changing the flow oi current in the calling line to actuate said meter, and means tor preventing the momentary release oi said relay due to said current change trom ailecting said signal.

7. In a telephone system, a calling line and a called line, means tor interconnecting said lines for conversation, a register at the substation oi the calling line, a supervisory relay in circuit with the calling` line, a supervisory signal controlled by said relay, means for periodically reversing the dow of current in the calling line to actuate said register, and means iter preventing the momentary release oi' said relay from atiecting said signal.

8. In combination, a telephone line, a supervisory relay in circuit with said line, a supervisory signal, a second relay arranged to release in response to a prolonged de energization of the rst relay but not to respond to momentary releases thereof, a mechanism controlled by the second relay `for intermittently actuating said signal, and means controlled by said second relay while energized for maintaining the supervisory signal in a given condition.

9. In a telephone system, a calling line and ay called line, means for establishing a connection between said lines, a supervisory relay in circuit with the calling line, a supervisory signal, means ier operating said signal intermittently, and a second relay for preventing` the momentary release ot1 the supervisory relay from aii'ecting said signal.

1 0. In a telephone system, a calling line and called line, means tor establishing a connection between said lines, a supervisory relay in circuit with the calling line, a supervisory signal, means controlled by said relay `for actuating s aidsignal intermittently,-

and a second relay Controlled by the super.- visory relay for preventing the' momentary release of the supervisory relay from affecting said signal.

l1. In a telephone system, a subscribers line, a ysuper,visory signal for said line, a circuit for said signal including means for actuating the lsignalintermittently, a supervisory relay for closing said circuit, and means for disabling said circuit, said last means being non-responsive to certain operations of vsaid supervisory relay and responsive toother Operations of said relay to 'f again render said signal effective.

V12. `In a telephone syst-em, a telephone line and means for establishing a connection with said line, a. supervisory signal for said line, a circuit for said signal, a supervisory relay y for closing said circuit to render the signal efective, a second relay effective to reinove the `control of said signal from the supervisory relay, and a circuit for the second relay controlled by the supervisory relay, said second relay being responsive to certain operations of lthe supervisory relay to restore the controlof said signal to said super- Y visory-relay but non-responsive to other operatrons jof said supervisory relay.

In witness whereof I hereunto subscribe my name this 7th day of January, 1928.

A CLARENCE B. FOWLER. 

